This is cmod, which provides modularized initialization of environment
variables such as PATH. Once cmod is installed and configured typing
“module add tex” might add /sw/tex/teTeX/bin/sparc-solaris2.5.1 to
PATH, /sw/tex/teTeX/man to MANPATH, etc. Cmod provides a way for the
system administrator to define module files (such as “tex”) that
modify the environment in well-defined ways. It allows the user to
select the modules that should be active; the user can also override
the modules provided by the administrator.